The use of electrostatic precipitators to remove particulate matter from a fluid stream is known. See, e.g., U.S. Pat. No. 4,247,307 to Chang, U.S. Pat. No. 4,194,888 to Schwab et al. Typically, an electrostatic precipitator comprises a charged electrode, generally a straight wire, contained within grounded collector plates or pipes. Ionized particles are drawn by the electric field created between the electrode and the collectors. Particularly popular of late are "wet" electrostatic precipitators, in which a flow of a cleaning fluid, such as water, is maintained over the collector plates which washes away the particulates as they collect on the collectors. This eases the cleaning process, but also improves electrical conduction of the collectors.
Chang et al. describes a single stage precipitator which includes an electrode having regularly spaced round plates that are fixed perpendicularly to a conventional wire. This creates separate and alternating charging and collection sections of the electrode; the charging sections being in the cross sections of the precipitator in the immediate vicinity of a plate, and the collection sections being in the cross-sections somewhat removed from a plate (i.e., along the portions of wire between plates). This type of precipitator can be driven by a single power source; however, because the wire is considerably farther from the collector surface than the plates, the electric field in the collection sections is much weaker than that in the charging sections. This alternating arrangement of small crosssections having a strong electric field with large cross-sections having a considerably weaker electric field is somewhat inefficient and requires a relatively long series of collection sections in order to remove an acceptable percentage of particles from the stream. Schwab discloses a similar configuration, but includes a series of plates which increase in diameter toward the downstream end of the electrode in an attempt to improve collection efficiency. Others have utilized separate charging and collection zones driven by separate power sources in an attempt to address the problem.
In view of the foregoing, it is an object of this invention to provide a single power source electrostatic precipitator with improved collection efficiency.
It is a further object of the present invention to provide a single power source electrostatic precipitator that can be fitted easily into existing flue gas decontamination streams.